One option for processing a vacuum resid portion of a feedstock is to perform a deasphalting process on the resid to form deasphalted oil. An aromatics extraction process can then be performed on the deasphalted oil to generate a brightstock raffinate. The brightstock raffinate can then be solvent dewaxed. This generates a dewaxed brightstock that is suitable for use as a lubricant base stock and a remaining waxy product that can be referred to as petrolatum. Conventionally, petrolatum has been used a feedstock for catalytic cracking processes to form fuels. Alternatively, petrolatum can be used as a microcrystalline wax product.
European Patent EP0788533B1 describes a wax hydroisomerization process for producing base oils. Petrolatum is identified as a potential feed for the process. When petrolatum is the feed, the petrolatum is initially hydrocracked to generate 15 wt %-25 wt % conversion of the feed. This conversion is relative to a conversion temperature of 650° F. (343° C.). The hydrocracked feed is then exposed to an isomerization catalyst, which is described as a large pore zeolite or silico-alumino phosphate molecular sieve with at least one 12-membered ring in the molecular sieve structure. Zeolite Beta, zeolite Y, and mordenite are provided as examples of large pore molecular sieves. The isomerization is described as having a conversion relative to 650° F. (343° C.) of 5 wt % to 30 wt %. In order to meet a desired pour point, the hydrotreated, isomerized feed can then be exposed to a dewaxing catalyst. The dewaxing catalysts are described as molecular sieves with 10-member rings in the molecular sieve structure, such as ZSM-22, ZSM-23, or ZSM-35. Dewaxing is described as causing an additional conversion loss of 10 wt % to 20 wt %. It is noted that the overall lubricant base oil yield is described as also being reduced based on the amount of wax remaining in the sample after the various processes. PCT Publication WO 96/07715 describes a similar type of hydroprocessing scheme.